Abstract

The micellar solution of a surface active ionic liquid, 1-hexadecyl-3-methylimidazolium tetrafluoroborate (C₁₆mimBF₄), with the presence of organic salt sodium salicylate (NaSal) was investigated by rheological measurements and ¹HNMR. According to steady-shear viscosity curves, with the increase of NaSal concentration, the zero-shear viscosity η₀ firstly showed an increase which meant the gradual formation of wormlike micelles in solutions (the most optimal concentration of NaSal was 4.5 mM), then η₀ decreased to the previous value which indicated the wormlike micelles were destroyed. And the results of ¹HNMR were further verified the structure transformation. The C₁₆mimBF₄/NaSal solution showed special viscoelastic property with the increase of NaSal concentration. When the linear wormlike micelles formed, the mixture solutions had viscosity (G′<G″). When the branched wormlike micelles formed, the elastic property was prominent (G′>G″). In the frequency sweep rheological measurements, the curves of G′ and G″ showed two intersections, which indicates the structure of long wormlike micelles is weak and may be cut into short ones at higher shear frequency.

摘要

通过流变学测量和¹ HNMR研究了表面活性离子液体 1-十六烷基-3-甲基咪唑鎓四氟硼酸盐 (C ₁₆ mimBF ₄ )的胶束溶液，其中存在有机盐水杨酸钠 (NaSal) 。根据稳态剪切粘度曲线，随着NaSal浓度的增加，零剪切粘度η ₀先增加，这意味着溶液中逐渐形成蠕虫状胶束（NaSal的最佳浓度为4.5 mM），然后η ₀降低到先前的值，表明蠕虫状胶束被破坏。¹ HNMR结果进一步验证了结构转变。C ₁₆mimBF ₄ /NaSal溶液随着NaSal浓度的增加表现出特殊的粘弹性。当线性蠕虫状胶束形成时，混合溶液具有粘度（G'<G”）。当分枝的蠕虫状胶束形成时，弹性性能突出（G'>G'）。在扫频流变测量中，G′和G″曲线呈现两个交点，表明长蠕虫状胶束结构较弱，在较高的剪切频率下可能被切割成较短的胶束。